This invention relates to the assembly of turbine blades by pressure welding to a hub or disk to form a bladed disk, or "blisk", and more particularly to such a method that assures accurate positioning of a preformed blade component with a preformed blade root or stub element on the hub.
Welding of flow directing blades to hubs of turbine rotors or stators by pressure or other welding techniques requires accurate positioning of the blade element, especially establishment of correct airfoil leading and trailing edge alignment. This has been accomplished through complex and expensive jigs and clamps, use of withdrawable mandrels, or costly machining of parts to have cooperating interdigitation of elements that remain after welding.
The rotational positioning of airfoil blade outer halves with preformed blade stubs or inner halves is rendered particularly difficult by the compound curves that are characteristic of the blade to produce progressively changing airfoil sections along the length thereof.
With the foregoing in mind, it is a principal object of the invention to provide a method of, and components for, effecting accurate positioning of blade components during pressure welding without the need for complex jigs, clamps, or mandrels.
Another object of the invention is to provide a method of assembly utilizing pressure welding and which is more reliable and economical and which results in a finished turbine blade and hub that is free of included keys, pins, mandrels or other alignment devices that might provide a locus for failure under stress.
As yet another object, it is an aim of the invention to provide a method for fabrication of turbine flow directing rotors or stators having a disk or hub and an upper airfoil or blade pressure welded to a lower airfoil or blade stub on the disk, the method being characterized by the provision of excess flash or flanges on the upper and lower airfoils, providing the flanges with locating holes, providing disposable dowels or alignment pins in said holes, pressure welding the blade and stub, including their flanges and pins, togethr, and machining away the excess flange material and pins.
Other objects and many of the attendant advantages will be readily appreciated as the subject invention becomes better understood by reference to the following detailed description, when considered in conjunction with the accompanying drawings.